Both pressure ulcers (PUs) and ventilator associated pneumonia (VAP) commonly occur as iatrogenic complications in the critically ill, resulting in increased morbidity, mortality, and health care costs. In mechanically ventilated patients, strategies to prevent these complications are in conflict. Recommendations to reduce pressure ulcer (PU) risk place patients in backrest positions of less than 30 degrees while interventions to reduce VAP risk place patients in backrest positions of greater than 30 degrees. Although it is well documented that higher backrest elevations reduce VAP, there is little empirical evidence that describes the effect of these higher backrest positions (30 degrees or greater) on factors affecting PU formation and tissue integrity. The purpose of this descriptive, longitudinal study in critically ill mechanically ventilated adults is to 1) describe the effect of backrest elevation on skin pressure and sheer force and, 2) describe the effect of backrest elevation on tissue integrity. A secondary aim will evaluate the effect of intrinsic (patient) factors (demographics, physiologic status, support surface, mobility) on extrinsic factors (pressure, shear, moisture) and tissue integrity. A total of 150 subjects from 3 adult ICUs will be enrolled over a 24 month period. Backrest elevation, pressure and shear force will be measured continuously for 72 hours. Backrest elevation will be measured using an inclinometer device and pressure and shear will be measured using the XSENSOR pressure mapping system. Tissue integrity will be measured every 12 hours by skin observation using the NPUAP Staging System and a measure of tissue injury (EPISCAN). Sedation level will be continuously measured (for 72 hours) by processed EEG (PSI) and patient movement (wrist actigraphy) will be documented. Severity of illness (APACHE III), nutritional status (prealbumin) and type of support surface will also be obtained. All data will be collected by research team members and downloaded to a computer for analysis. Stepwise, multivariate repeated measures models will be used to describe the relationships among elevation levels, skin pressure, shear force and tissue integrity over time. This study will make a significant contribution to our understanding of pressure levels and duration that result in tissue injury in the critically ill and to the empirical base of PU development. PUBLIC HEALTH RELEVANCE: Pressure ulcers occur often in the critically ill. Use of elevated backrest positions are helpful to reduce pneumonia in this population but may also increase pressure ulcers. This study will evaluate use of elevated backrest position to determine its effect on tissue and skin integrity. Factors that may influence pressure ulcer risk in the population will also be explored.